[HE] IPv6 - ShibbyMod /48 not working + br1 IPv6 possible?

i had setup a Routed /64 via HE Tunnelbroker and had no issues so far. No i wanted to Switch to /48 (to serve my 2nd router IPv6).
I entered the Routed /48 address from HE and set Prefix length to 48, pressed tab and save. But its only working for the Router itself via br0 - my Windows 7 machine says: No Internet connectivity as RAs are only link-local:

So what am i doing wrong?

And how to configure IPv6 for the second router behind the first? Do i set there "Native IPv6" from ISP? Or what to set there?
How to subnet the /48 in /64? :S Mine is:
2001:470:7308::/48
so the /64 are:
2001:470:7308:1::/64
2001:470:7308:2::/64 e.g.?

And can i configure IPv6 for br0-3 or only br0?

Many thanks in advance! I appreciate any help you can provide to an IPv6 Newbie..